Granulating apparatus

ABSTRACT

Apparatus for granulating loose, fine-grained and/or powdered materials comprising a rotary drum and a separately driven system of granulating tools. The tools are generally wedge-shaped and spaced at constant radial distances from the drum wall. The axial distance between adjacent tools decreases from the points to the rear ends thereof, thereby subjecting the material to a continual axial pulsating compression with subsequent expansion, thereby enhancing the granulating effect. The drum can be driven in opposite directions or at a faster or slower rate than the tools whereby optimum granulate formation can be achieved.

United States Patent [1 1 [111 3,825,193 [451 July23, 1974 Lodige et al.

1 GRANULATING APPARATUS [76] Inventors: Wilhelm Lodige, Elsenerstr. 9c;

Fritz Lodige, Leuschnerstr. 12; Josef Lucke, Im Lonfeld 15; Karlheinz Luke, Detmolder Str. 27, all of Paderborn, Germany [22] Filed: Apr. 14, 1972 [21] Appl. No.: 244,152

[30] Foreign Application Priority Data Apr. 15, 1971 Germany 2118231 [52] US. Cl. 241/187, 241/188 R, 241/195 [51] IIIL CI. 1302c 13/06, 13020 13/28 [58] Field of Search..... 241/188 R, 187, 154, 292.1, 241/191,195,199.1, 46.17, 46.11, 46.15

A [56] References Cited UNITED STATES PATENTS 91,343 l/1869 Jackson 241/191 1,458,387 6/1923 Bourne 241/187 X 2,358,827 9/1944 Rakowskyet al.... 241/46.17 X 2,852,200 9/1958 l-lolzer 241/46.1l

3,027,102 3/1962 Lodige et al 241/46.17 3,329,350 7/1967 Wisgerhof et a1 241/187 X 3,420,454 l/1969 Brown 241/188 R UX 3,555,996 1/1971 Schwarz et a1 241/154 X Primary Examiner-Granville Y. Custer, Jr. Assistant Examiner-Howard N. Goldberg Attorney, Agent, or Firm-Donald D. Jeffery [5 7 ABSTRACT Apparatus for granulating loose, fine-grained and/or powdered materials comprising a rotary drum and a separately driven system of granulating tools. The tools are generally wedge-shaped and spaced at constant radial distances from the drum wall. The axial distance between adjacent tools decreases from the points to the rear ends thereof, thereby subjecting the material to a continual axial pulsating compression with subsequent expansion, thereby enhancing the granulating effect. The drum can be driven in opposite directions or at a faster or slower rate than-the tools whereby optimum granulate formation can be achieved.

' 6 Claims, 4 Drawing Figures l GRANULATING APPARATUS BACKGROUND OF THE INVENTION Additions of pigments are preferably employed in orderto improve the proportioning capacity of granulated materials. Especially small amounts of additions can, in automatic weighers, be rather precisely proportioned in granulated, readily trickling form.

A rationale for smelting ground iron ores in pellet form consists, among other considerations, in a better ore yield and more economical power utilization in the blast furnace process.

Thus, a multiplicity of granulating devices operating accordingto the rotary drum principle were developed in various branches of industry for a great many different granulation purposes.

The size, shape and strength of the pieces of granuopposite inclination, whirls up the material to be moistened in the drum and throws material portions against each other. Due to the crosswise throwing against each other of these portions of the loosened-up material, while air is enclosed and water is simultaneously added, an agglomeration effect is achieved. The position of the worm gear in the drum and the effect of this worm gear do not permit a gradual, uniform rolling-up of the powder product into granulates but form porous clumps, full of fissures and of undefined shape.

All known granulating devices in the form of rotary drums present the common disadvantage of being limited to a definite field of use since they are designed for the product to be granulated and constructed according to the concept thereby specified.

.SUMMARY OF THE INVENTION The present invention aims at providing an apparatus free fromthe aforementioned shortcomings and adaptable, in a simple manner, and without constructional changes, to the most varied granulating properties of the loose, finely grained and/or powdered products to be granulated.

To solve this problem, the invention provides an ap-, paratus of the general type mentioned above in combination with a separately driven and rotating granulating tool system which moves centrally in the rotary drum and relative to the inner wall thereof. The tools are spaced at constant radial distances from the drum wall,

0 while the axial distance between adjacent tools delated material depend very strongly on constant machine factors, such as length and diameter, and on devices which can be modified only by'structural means.

In most cases, deposits are formed in rotary drums, which are not always desirable, especially when they become too large. This can be remedied by the use of skimmers consisting of scrapers, rollers, or endless screws. However, such additional installations usually counteract a uniform granulate formation.

From the German Pat. 936,033 a process and a corresponding device for soot granulation are known, in which, for preventing a soot deposit, a wire basket rotates inside the rotary drum at a higher or lower speed than the drum. It is obvious that such a proposal does not present a measure which promotes the built-in granulation. Moreover, it remains without effect when the meshes of the wire basket become sticky andconsequently are clogged. Therefore, the insertion of this device will be limited to soot granulation.

Furthermore, in German Pat. 1,262,238 a granulating drum is described in which the material that rolls up when the drum rotates is alternately slightly compacted and expanded by fixed semi-circular baffle plates which rotate along with the drum. These baffle plates present the great disadvantage that they make structurally impossible the additional installation of deposit-reducing devices, such as rollers or scrapers. For this reason the use of such a granulator is possible only to a very limited extent in moist granulation, so that in practice it is restricted to dry granulation with products not subject to deposit formation.

For the lumping of powder, for example, cementitious material, a further apparatus is explained in German Pat. 706,090, wherein a worm conveyor, eccentrically positioned in a rotary drum and having sections of creases from the points to the rear ends thereof. Individual metal sheet covers permit a gradual changing over, at the rear ends of the tools (relative to the direction of rotation), to a .round shape parallel to the rounded section of the rotary drum. Thus, this apparatus is provided with a cylindrical rotary drum with tools rotating therein centrally about the longitudinal drum axis and movable relative to the inner drum wall. The advantageous adaptability is based on the relative speed, according to the invention, of the motion of the drum and the tools about a common center. Thus, various relative motions can be set according to the invention by securing the tools in position while only the drum rotates, or permitting the tools to be driven in the same direction but at the same speed or at a faster speed than the drum. The deposit layer forming in moist granulations at the inner drum wall cannot become heavier than permitted by the distance, constant everywhere, of the granulating tools from the inner drum wall, since a deposit that grows beyond this distance is continuously scraped off in a delicate manner by the edges of the tools and refed to the granulating process in a fine form.

According to a practical embodiment of the invention comprising a drum-shaped container supported by rollers, at least one of which may be a driving pulley, the tools are mounted on a rotatable shaft, supported inside and outside the container and extending concentrically relative to the drum. This makes it possible to turn the container with respect to the tools mounted on the shaft, which may be stationary, or, alternatively, the tools are capable of being driven independently of the rotary motion of the drum.

The granulating tools of the invention are wedgeshaped, seen in the direction of rotation, and consist of three parts, namely, two lateral parts which form the wedge of the invention, and one metal sheet cover facing the drum center. Each tool is spaced at a constant radial distance from the drum wall, and the lateral parts are covered in such a manner that the cover sheet forms at the rear end of the tool a stepless transition to the container curvature. The tools are distributed in at least two, and preferably three or more, rows along the periphery of the shaft and fastened to arms, the axial distance between two adjacent tools, due to the wedgelike shape thereof, being larger at the tool points than at the end. Preferably, the reduction in distance should first be greater and then decrease as the tool length in creases.

The two ends of the rotary drum are partly closed with annular diaphragms. At the front side provided for the the material supply, the diaphragm aperture is preferably one-third larger in diameter than the diaphragm aperature provided for the discharge of the material.

BRIEF DESCRIPTION OF THE DRAWING The drawing shows the granulating apparatus of the invention, in which FIG. 1 is a longitudinal sectional view of the entire apparatus;

FIG. 2 is a cross-sectional view taken along line II II of FIG. 1;

FIG. 3 is a sectional view of two adjacent granulating tools taken on line III-III of FIG. 2, and

FIG. 4 is a perspective view of the granulating tools.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The apparatus shown in FIGS. 1 and 2 comprises a cylindrical drum 1 supported on rollers 2 so as to rotate about its longitudinal axis. Drum 1 can be driven in various ways, for example, by means of an adjustable drive, not shown, which acts upon at least one of the rollers 2.

Extending centrally through the drum 1 is a shaft 3 on which are mounted radial arms 4 for mounting the granulating tools 5. In FIGS. 1 and 2, the tools 5 have also been illustrated as 50, 5b and 5c in order to distinguish one row of tools from the others, although it should be understood that the tools are identical. In the embodiment shown, shaft 3 is supported in a bearing 6 outside drum 1 and in a bearing 7 supported by spokes 8 within drum 1, and is driven by an infinitely variable drive 9, shown diagrammatically in FIG. 1. Each of the tools 5 includes two lateral parts commonly designated at 13 and a metal sheet cover 14 which extends between and thus encloses one side of the lateral parts 13. The radial arm is permanently connected to the cover 14, as shown by the weldments in FIG. 2.

The symbols n, and n, and the corresponding arrows in FIG. 2 indicate that drum 1, and shaft 3 with the granulating tools 5, can be driven at different speeds, and drum 1 can be rotated in the opposite directions. While in such opposite direction of rotation of the drum, the shaft 3 can if desired be held stationary thereby leaving the tools 5 at rest.

At the feeding and discharge ends of the drum 1, annular shutters l0 and 11, respectively, are provided. The entire apparatus can be adjusted, by means of an indicated tilting support 12, so as to slant toward the discharge end.

FIG. 3 illustrates the wedge-shape of the granulating tools 5, this wedge covering the length L of the tools.

In'the embodiment shown, the wedge point A-B is blunter along somewhat more than half of length L than in the remaining rear section B C. The lateral metal sheets 13 which form the wedge are shown in section, and the covers 14 appear in elevation. The effect achieved by the tools is that the axial distance between adjacent tools 5 in the drum is largest between wedge points A, decreases sharply between points A and the points marked B, and decreases gradually from points B to the ends C of the tools 5.

A normal granulating process is described in the following example. The product which has been previously mixed, for example, in a drum mixer having mixing tools rotating therein and operating preferably according to known centrifugal and whirling methods, and which has been moistened with a liquid, for example, water, is continuously supplied to the drum 1 by way of feeding device 15 shown diagrammatically as a proportioning screw which extends through shutter 10. The material is supplied while the drum 1 and tools 5 rotate in the same direction and while n n The product is first lifted at one side up to an angle of slope which depends on the product. Then after passing this angle, it begins to roll up usually on its surface of constant slope, and is distributed, due to the continued material supply, over the entire drum length.

Due to the somewhat higher speed, the granulating tools 5 overtake drum 1 and the product rolling therein which during the overtaking process is forced to pass through a narrowing track between two tools 5, wedgeshaped according to the invention.

After each passage of the tools, the product again expands but is narrowed down again at the following passage of the tools. In this manner the product which rolls up on the inner wall of drum 1 is subjected to a continual axial pulsating compression with subsequent expansion, which is very conducive to granulate formation. Particularly, the shape and strength of the individual granulated material grains and the grain spectrum are thereby affected. An advantage of the invention consists in that the extent of influence on the granulate formation can be controlled by the speed of the shaft and thus by the frequency and strength of the pulses produced in the material.

Afurther advantage resides in the fact that the product deposits formed in most cases cannot exceed the thickness which corresponds to the distance between the drum and the tools, since the edges of the tools continuously scrape off the deposit. An even, uniformly thick deposit is thus formed, especially since the paths of granulating tools 5 overlap, as seen along the length of drum 1.

When the product present in the drum has risen to the radially inner edge of the supply shutter 10, the drum is lowered toward the discharge end through tilting support 12 by 2 to 5 until the finished granulate flows over the edge of the higher discharge shutter 11, where it can be collected by suitable conveyors, not shown. In practice the quantity of fresh material supplied in proportioned amounts is adjusted to the quantity of the discharged granulate.

During the granulating process care must be taken that the material continually carry out rolling motions and that no dropping sections for the material develop. For this reason, the metal sheet cover 14 of each wedge shaped granulating tool 5 is coextensive with the rounded lateral parts 13, so that the material which moves in the material layer above the tools can gradually roll off, without the formation of a dropping section, from the metal sheet cover 14 to the rounded drum section.

We claim:

1. Apparatus for granulating loose, finely grained materials comprising a rotary drum, means for rotating said drum, a separately driven system of granulating tools mounted in said drum in axially spaced arrangement, means for driving said tools independently of the rotation of said drum, said tools comprising a pair of lateral parts and a metal sheet cover secured to said lateral parts, said lateral parts being generally wedge shaped, with the leading edge of said wedge being in the direction of rotation of said tools, said tools being spaced at constant radial distances from the drum wall, the axial distance between adjacent tools thereby decreasing from said leading edges of said wedges to the rear ends of said tools, said covers being shaped and so mounted on said lateral parts as to form said tools at such rear ends into a round section generally parallel to the rounded section of the rotary drum.

2. The apparatus of claim 1 further including means for driving said rotary drum in the same direction of rotation as said granulating tools but more slowly than the latter.

3. The apparatus of claim 1 further including means for rotating said drum in a direction opposite to that of the motion of the tools.

4. The apparatus of claim 1 further including at least three rows of axially adjacent wedge-shaped tools uniformly distributed over the periphery of said drum.

5. The apparatus of claim 1 further including rollers for supporting rotative movement of said drum, at least one of such rollers being a drive pulley, said tools being mounted on a shaft supported both inside and outside said drum.

6. The apparatus of claim 1 wherein said rotary drum includes supply and discharge ends, said supply end being formed with a shutter opening approximately one-third larger in diameter than a shutter opening formed in said discharge end of said drum. 

1. Apparatus for granulating loose, finely grained materials comprising a rotary drum, means for rotating said drum, a separately driven system of granulating tools mounted in said drum in axially spaced arrangement, means for driving said tools independently of the rotation of said drum, said tools comprising a pair of lateral parts and a metal sheet cover secured to said lateral parts, said lateral parts being generally wedge shaped, with the leading edge of said wedge being in the direction of rotation of said tools, said tools being spaced at constant radial distances from the drum wall, the axial distance between adjacent tools thereby decreasing from said leading edges of said wedges to the rear ends of said tools, said covers being shaped and so mounted on said lateral parts as to form said tools at such rear ends into a round section generally parallel to the rounded sEction of the rotary drum.
 2. The apparatus of claim 1 further including means for driving said rotary drum in the same direction of rotation as said granulating tools but more slowly than the latter.
 3. The apparatus of claim 1 further including means for rotating said drum in a direction opposite to that of the motion of the tools.
 4. The apparatus of claim 1 further including at least three rows of axially adjacent wedge-shaped tools uniformly distributed over the periphery of said drum.
 5. The apparatus of claim 1 further including rollers for supporting rotative movement of said drum, at least one of such rollers being a drive pulley, said tools being mounted on a shaft supported both inside and outside said drum.
 6. The apparatus of claim 1 wherein said rotary drum includes supply and discharge ends, said supply end being formed with a shutter opening approximately one-third larger in diameter than a shutter opening formed in said discharge end of said drum. 